Chembarambakkam Lake - A lifeline that ravaged Chennai

Chembarambakkam Lake, now being blamed for the City’s flooding, was once the lifeline of South Chennai as it irrigated 168 villages in the district while the North of Chennai benefitted from Puzhal Lake. However, plundering of water bodies including the lake, has now led to the uprooting of livelihoods and homes over a vast area.

 

“Chembarambakkam was known as Puliyur Kottam. It is one of the 24 kottams (villages) that existed even during the later Chola period in Thondai Mandalam which had Kancheepuram as its headquarters,” J. Mohan, an engineer by training and an expert on Thondai Mandalam said.

Adayar is the major river that carries water from Chembarambakkam to South Chennai and innumerable oodais (canals) originating from Adayar brought water to paddy fields. All ancient literatures of Thondaimandalam have a reference to Chembarambakkam. 

The recent floods in the Adyar river have left many residents wondering about flooding in areas that are usually not vulnerable.

The reason is that the Chembarambakkam reservoir, which chiefly contributed to floods in Adyar river, received the highest inflow in 100 years on December 1, much more than the capacity fixed based on flood data of 60 years.

The reservoir’s capacity was last improved in 1996 to handle an inflow of 33,400 cubic feet per second (cusecs). This equals to nearly 10 lakh litres per second. Sources say that the reservoir received was more than 35,000 cusecs on the midnight of December 1,2015

“If 35,000 cusecs were released into the river, it would have only taken three hours for the flood. But, the discharge was moderated to 29,400 cusecs that took six to nine hours for the floods to flow into the river. We could not have discharged lesser volume of water as the inflow was beyond the reservoir’s capacity to handle,” said the official source.

Discharge is moderated according to the inflow and the rainfall over the waterbody. Normally, the reservoir’s levels are maintained two feet lower than the maximum level during the rainy season. This is to accommodate stepping up storage when the inflow is less.